Mining the Galactic halo for very metal-poor stars

S. Salvadori, A. Ferrara, R. Schneider, Evan Scannapieco, D. Kawata

Research output: Contribution to journalLetterpeer-review

67 Scopus citations


We study the age and metallicity distribution function (MDF) of metal-poor stars in the Milky Way halo as a function of galactocentric radius by combining N-body simulations and semi-analytical methods. We find that the oldest stars populate the innermost region, while extremely metal-poor stars are more concentrated within r < 60 kpc. The MDF of [Fe/H] ≤ -2 stars varies only very weakly within the central 50 kpc, while the relative contribution of [Fe/H] ≤ -2 stars strongly increases with r, varying from 16 per cent within 7 < r < 20 kpc up to ≥40 per cent for r > 20 kpc. This is due to the faster descent of the spatial distribution (as seen from Earth) of the more enriched population. This implies that the outer halo < 40 kpc is the best region to search for very metal-poor stars. Beyond ~60 kpc the density of [Fe/H] ≤ -2 stars is maximum within dwarf galaxies. All these features are imprinted by a combination of (i) the virialization epoch of the star-forming haloes, and (ii) the metal enrichment history of the Milky Way environment.

Original languageEnglish (US)
Pages (from-to)L5-L9
JournalMonthly Notices of the Royal Astronomical Society: Letters
Issue number1
StatePublished - Jan 2010


  • Cosmology: theory
  • Galaxies: evolution
  • Galaxies: stellar content
  • Stars: formation
  • Stars: population II
  • Supernovae: general

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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